1. Field of the Invention
This invention relates to a shock absorbing device of a single lens reflex camera, and in particular to a shock absorbing device which effectively works against vibrations caused by a mirror pivoting rapidly.
2. Description of the Prior Art
In a single lens reflex camera having a mirror pivotable between an observation position for bending the photo-taking optical path toward the finder and a retracted position in which the mirror has been retracted out of the photo-taking optical path, the camera body has heretofore been displaced in a direction opposite to the direction of the movement of the mirror as the reaction of the rapid pivoting of the mirror to cause vibrations of the camera. A device in which a counterweight is provided at the tip end of a pivotally movable lever having a center of pivotal movement near the center of pivotal movement of the mirror and having a long arm, and in which this counterweight is pivoted in a direction opposite to the direction of pivotal movement of the mirror to negate the reaction of the pivotal movement of the mirror is known from U.S. Pat. No. 3,860,941.
In this known device, however, the counterweight is designed to pivot sideways of the mirror so as not to intercept the photo-taking light beam and therefore, it is necessary that a wide space sufficient for the pivotal movement of the counterweight be provided laterally of the mirror, and this is contrary to the tendency of cameras toward compactness.
In order to eliminate such disadvantage, the inventors propose in U.S. Pat. No. 4,458,998 a shock absorbing device in which a counterweight is provided in the space between a mirror in the observation position and a film opening and the distance of movement thereof is made smaller than the distance of movement of the center of gravity of the mirror and the mass thereof is made sufficiently great by using a material of great specific gravity to thereby increase the vibration preventing effect. In the device disclosed in this prior art, the counterweight is designed to effect an arcuate movement along the bottom wall of a mirror chamber so that the counterweight is downwardly retracted out of the photo-taking optical path when the mirror is upwardly retracted out of the phototaking optical path. Accordingly, at the early stage of the movement of the mirror from the observation position, the counterweight moves in a direction opposite to the direction of movement of the mirror to thereby suppress the vibrations of the camera efficiently, whereas at the middle stage and thereafter, the counterweight moves in a direction perpendicular to the movement of the mirror so as to be along the bottom wall of the mirror chamber and therefore, it hardly suppresses the vibrations of the camera, and this leads to a disadvantage of low efficiency. Also, where the counterweight is designed to be pivoted vertically like the mirror in order to eliminate such disadvantage, extra space is required at the bottom of the mirror chamber, and this is contrary to the tendency of cameras toward compactness.